The Oviedo Arsenal
The Oviedo arsenal, technically the Fabrica de Armas de Oviedo, is located on the outskirts of the city of Oviedo, which is close to the north coast of Spain in the province of Asturias.  I have little inside information about the facility, so most of my information is from secondary (or more distant) sources, or gleaned from studying serial numbers and dates.  The following rifles were manufactured there: 

1)  Model 1893 long rifles, from 1896 to about 1928.  Estimated number made is a little over 500,000. The average yearly production for the "regular" serial number progression series, which I have the most data on, is estimated to be about 14,500 per year.  Production rate appears to be quite constant (see the graph on the Model 1893 page).  Beginning in 1928, the Oviedo arsenal apparently refurbished existing Model 1893's by adding a an internal barrel sleeve.  These rifles were reserialed with an "RE" prefix, later an "REA" prefix, presumably after 10,000 of the "RE" series were refurbished..

2)  Model 1895 carbines, dates observed from 1897 to 1919.  Estimated production of about 85,000, annual production of about 4000 per year.

3)  Model 1916 rifles with Oviedo marking, from 1916 to about 1936.  Estimated total number made of about 325,000, estimated production rate of 18,000 rifles/year.  Production rate appears to be quite constant (see the graph on the Oviedo Model 1916 page).

4)  Model 1916 carbines, unmarked.  No way to estimate dates or rates of production, but the total is estimated to be only about 10,000 rifles.  My guess is that these are not new production.

5)  Model 1916 rifles, unmarked.  If my current theory (until proven wrong, possibly tomorrow) is correct, these are not new production, but all refurbished and reserialed  This means that the Oviedo arsenal was involved exclusively in refurbishing rifles rather than new production after 1936.

Add all these numbers up, and the total production at Oviedo excluding refurbished arms was a little less than a million rifles.
The production figures given above are significantly lower than the ones in some of the references.  One reference states that about 2 million Model 93's were produced at Oviedo along with an unknown number of Model 1916's.  This would make total production including carbines and Model 1916's of about 5 million rifles.  My feeling is that this figure is way too high, and I offer the following supporting data/reasoning.

Gerald Howson's
Arms for Spain states that just prior to the Spanish Civil War, in 1936, there were "500,000 or so rifles in Spain".  Up to 1936, my estimate of total imports and production is as follows:
1)  About 325,000 rifles imported mostly from Germany in the 1890's. 
2)  About 500,000 Model 1893 long rifles produced at Oviedo
3)  About 350,000 Model 1916 rifles produced at Oviedo, most marked with the Oviedo logo
4)  Maybe about 100,000 carbines produced at Oviedo

Adding the above numbers gives a number for total production and imports of about 1,275,000 over about 50 years (from 1896 to 1936), which is consistent with Howson's figure.  Several million units produced up to that point with only a half million surviving examples doesn't sound plausible, particularly given the condition of most examples from this period.  Many have obviously been used quite a bit, and very few are unaltered, so it's hard to believe that there were millions of them.

According to information from Javier Sanchez, a Mauser collector who lives in Spain, the original plan in the 1890's was to improve the capacity at Oviedo to 20,000 rifles per year and get another 10,000 rifles annually from private industry.  The private capability never materialized, and it appears that the annual capacity at Oviedo never got to 20,000 rifles until 1916, when they started producing Model 1916's in addition to Model 1893's.  His reference is Rubi's book.    

It could be argued that with such a low annual production rate (less than 35,000 rifles annually, when both Models 1893 and 1916 were being produced), why even bother maintaining your own arsenal?  Why not simply contract with a foreign supplier, who could probably manufacture your annual production in less than a month?  In today's day and age when the typical purchasing manager's favorite word is "China", that is exactly what would happen.  My guess is that Spanish government saw a strategic necessity in maintaining their own arms production.  In the European climate of shifting alliances, you could be sure of a reliable supply only if you had your own arsenal.  It may have even been cheaper than purchasing from more advanced industrial nations such as Germany.  Low production rates of rifles was nothing new for Oviedo.  In 1891, the Oviedo arsenal made 2500 Winchester Model 1873 rifles for Royal Escort and Guardia Civil units.  By modern standards, this semi-prototype production seems absurd, but it happened.

The machinery used to produce the rifles was pretty basic - lathes and milling machines, little or no automation.  See the illustrations below.  The thumb cuts in the Model 1916 rifles are of varying depth, with no obvious pattern, which I assume means that they were milled out with the operator eyeballing the depth.         
This translates to "War Industries of Catalonia", and was a single factory or multiple workshops that were operated in or near Barcelona during the Spanish Civil War (1936-1939).  Model 1916 rifles were made there for the Republican army.  For the longest time, I thought this was a firearms "urban legend" - just a story that got passed around until it became a part of history.  I have since gotten enough evidence to convince me that the facility existed, but I still don't know much of anything about it.  Hoffman and Schott's book shows the "Industrias de Guerra de Cataluna" logo on a Model 1916 rifle along with the year 1938.  They also show a "Subsecretaria de Armamento" (Undersecretary of Armament) logo, also on a Model 1916 rifle produced in Barcelona in 1938.  Also, I have received several EMails with information about Republican produced arms that various people own. 

A picture in Carr's book
The Spanish Civil War in Pictures shows workers apparently straightening Model 1916 barrels in a Barcelona munitions factory.  Hugh Thomas states in The Spanish Civil War that rifle production in December of 1938 was 1000 per month.  His original source for this information is Soviet Army records.  Assuming that arms production was highest priority and was fully developed by 1938,, I have to assume that production was never much higher than this, so total production would have been less than 50,000 total rifles over the three years of the war.
Industrias de Guerra de Cataluna
The arsenals below produced Model 1893 and 1916 rifles.  There were other arsenals in Spain which produced other weapons, but they are outside the scope of this website
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Mauser Home Page
Page Updated
on 10/06/09
A Chronology of the Spanish Arsenal at Oviedo (at least where Mauser Models 1893 and 1916 are concerned, and a LOT of this is guesswork on my part):

1896:  Production of the Model 1893 rifle commences
1898:  Production of the Model 1895 carbine commences.
1916:  Production of the Model 1916 rifle commences
1927:  Production of the Model 1895 carbine concludes.
1928:  Production of the Model 1893 concludes, all Model 1893's from here forward are rebuilds
1933:  Production of rebuilt Model 1893's concludes, all Model 1893's from now on are converted to Model 1916's by adding the thumb cut in the left receiver wall.
1936:  Production of the Model 1916 concludes.
1939?:  The Oviedo arsenal goes back into production after the Civil War.  Model 1893's and 1916's have their crests scrubbed, gas escape holes and thumb cuts added as necessary,  and are converted to the "unmarked" Model 1916's.
1960? to ?  Many Model 1916's and 1893's are converted to 308 Winchester.
Model 1893 and 1916 Chronology at Oviedo
A couple of views of the Oviedo arsenal as it appears today.  Note the concrete wall topped with barbed wire that surrounds the arsenal as well as the city of Oviedo in the background.
Spanish Machinery
The illustrations below show machiniery at the Oviedo aresenal.  They come from a book entitled El Acero de Fabricacion de Fusiles, or "The Steel of Firearms Fabrication", written by Jose Boado y Castro in 1899.  John Wall was gracious enough to allow me to reproduce these images here (he has a copy of the book). 
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